As is known, integrated electronic devices are formed within dies, which are manufactured starting from wafers of semiconductor material and have, in plan view, a generally rectangular or square shape.
In detail, the edges and corners of the dies correspond to the so-called “scribe lines”, i.e., to the lines along which the wafers of semiconductor material are cut to form the dies themselves. In other words, the scribe lines define corresponding lateral surfaces of the dies.
In greater detail, each integrated electronic device can include a plurality of elementary electronic components, such as, for example, transistors, diodes, photodiodes, etc. Furthermore, given a generic die that houses at least one elementary electronic component, within the die it is possible to define a peripheral region (also known as “edge region”), adjacent to the scribe lines, and a central region, which is surrounded by the peripheral region and in which the at least one elementary electronic component is physically made. In addition, in the peripheral region there is usually provided a so-called edge-termination structure.
As is known, the edge-termination structures surround corresponding active areas, i.e., areas set within the central regions and housing the elementary electronic components. In use, the edge-termination structures perform the function of preventing onset of breakdown phenomena within the peripheral regions, which are more subject to the phenomenon of breakdown as compared to the central regions. In fact, the active areas, and hence the central regions, are typically designed so that the elementary electronic components housed therein can sustain (in theory) a maximum voltage Vmax, before the breakdown of the PN junctions present within said elementary electronic components occurs. Instead, within the edge regions, it is possible for breakdown to occur also at voltages much lower than the maximum voltage Vmax, with consequent limitation of the voltage that can effectively be applied to the elementary electronic components, and hence also to the integrated electronic device that houses them. In particular, the peripheral regions are more subject to the phenomenon of breakdown on account of the presence, in general, of corners and/or curvatures of doped regions, with consequent possibility, in use, of an increased density of the equipotential lines, i.e., an increase of the electrical field, to the point of causing breakdown of the semiconductor material that forms the peripheral regions.
For practical purposes, the edge-termination structures hence perform the function of reducing locally the intensity of the electrical field so as to prevent peaks of intensity of the electrical field in the proximity of the edges.
The presence of appropriate edge-termination structures is even more important in the case of integrated electronic devices formed at least in part not only of silicon but also of silicon carbide (SiC). In fact, within said integrated electronic devices very intense electrical fields are generated, which, in the central regions, are typically confined within portions made of silicon carbide, which has a critical electrical field higher than the critical electrical field of silicon. Instead, in the absence of appropriate edge-termination structures, it is possible, in the peripheral regions, for intense electrical fields to be generated also within silicon portions, with the consequent possibility of a breakdown occurring.